NATICK – Board of Health members said Thursday they don't feel they have enough information about a plan to use herbicide in Natick's part of Lake Cochituate.

"We're as committed as you're committed to public health of the citizenry," Board of Health Chairman Peter Delli Colli said. "We want to be absolutely sure there's not going to be any sort of problem (with herbicide diquat entering nearby wells)."

The commission in April approved an order of conditions allowing the state Department of Conservation and Recreation to use physical and chemical means to combat nuisance vegetation such as milfoil.

DCR plans to apply the herbicide Monday, weather permitting, but officials discussed Thursday contacting the state to see if it can delay the application, which would give the Board of Health more time to learn about the proposal.

Delli Colli asked commissioners to continue to help them feel more comfortable with treatment.

Conditions include an opt-out provision for people who do not want herbicide applied near their homes as well as establishing a buffer zone around wells where the herbicide will not be used. Chemical treatment cannot be done in areas where plant cover is 5 percent or less. Sediments and well and lake water will be tested for herbicide, among other requirements.

Conservation Commission Chairman Matthew Gardner said the commission has spent almost a decade examining the problem. Workers have tried numerous mechanical methods that have not worked. Yet, applying herbicide in the lake's North Pond in Wayland has led to predominately hand pulling in several years after the treatment.

"None of us are thrilled by the idea of using chemicals," Gardner said, but he said the plan being used is what state environmental officials recommend.

Conservation Agent Bob Bois said the commission is comfortable with the mix of chemical and mechanical means.

"We have exhausted all other options," he said.

The commission in its conditions took steps to protect the drinking water supply and used a "very, very conservative approach," Bois said.

Board of Health members suggested scaling back the application or delaying at least part of it a few weeks.

Bois said the science does not show a need for delaying the treatment, but a delay could make people feel better.

Natick right now cannot draw from its Elm Bank wells, which are not near Lake Cochituate, but it might be able to in two week's time depending on the flow in the Charles River, officials said.

Residents have had differing views on the use of chemicals. Some worry it could affect nearby wells while others think the treatment will help decrease plants that make it dangerous to swim in the lake and deplete the lake of oxygen fish and other species need.

Page 2 of 2 - Only seven people out of more than 300 who had an opportunity to opt-out decided to do so, according to DCR.

Gardner said he hopes to work on a mechanism where the Board of Health is involved during the review process for projects like this.